#include<stdio.h>

int main(){
    int x;
    scanf("%d",&x);
    x/=10;
    switch(x){
        case 10:
        case 9: printf("A"); break;
        case 8: printf("B"); break;
        case 7: printf("C"); break;
        case 6: printf("D"); break;
        case 5: 
        case 4: 
        case 3:
        case 2:
        case 1:
        case 0: printf("E"); break;
        default: 
    }
    return 0;
}